The Experts below are selected from a list of 23286 Experts worldwide ranked by ideXlab platform
Xulong Wang - One of the best experts on this subject based on the ideXlab platform.
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a carrier based modulation scheme to reduce the third Harmonic Component of common mode voltage in a three phase inverter under high dc voltage utilization
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Jin Huang, Quanhui Liu, Xulong WangAbstract:High dc voltage utilization is one of the important requirements in a three-phase inverter. Under some carrier-based pulse width modulations (PWMs), the dc voltage utilization can reach the same maximum as that under the space vector modulation. But the third Harmonic Component of common-mode voltage (CMV) will be increased markedly while using these carrier-based PWMs in inverters. To improve the situation, this paper proposes that a midpoint-fluctuation carrier (MFC) scheme should be used in the three-phase inverter. The MFC is formed by adding a midpoint-fluctuation signal on the standard symmetrical triangular carrier. By analyzing the linear modulation region of the midpoint-fluctuation signals, a minimum fluctuant signal in the linear modulation region is designed in the paper. Compared with the use of other conventional schemes in the three-phase inverter, the use of minimum MFC scheme has higher fundamental amplitude in the output line voltage and smaller magnitude of the third Harmonic in the CMV. The feasibility and validity of the MFC are proved by experiment results in a three-phase inverter.
G W Jewell - One of the best experts on this subject based on the ideXlab platform.
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analytical modeling and finite element computation of radial vibration force in fractional slot permanent magnet brushless machines
IEEE Transactions on Industry Applications, 2010Co-Authors: Lijian Wu, G W JewellAbstract:An analytical model has been developed for analyzing the radial vibration force in fractional-slot permanent-magnet machines. It is compared extensively by finite-element analyses and used to investigate the influence of the following: 1) stator slotting; 2) tangential field Component; 3) radius in the air gap for computation; 4) load condition, etc. The major findings include the following: 1) even on an open circuit, the low Harmonic Component (e.g., the second for a 10-pole/12-slot machine) of the radial force exists due to the slotting effect, although the amplitude is relatively low, while the slotless analytical model cannot predict this phenomenon; 2) on a load, the slotless analytical model is accurate enough for the radial force analysis since the low-order Harmonic Component of the radial force is mainly due to the interaction between the magnet field and the armature-reaction field and is largely determined by the combination of the pole and slot numbers; 3) it is much more reliable to calculate the radial force in the middle of the air gap rather than close to the stator bore; and 4) the simple formula accounting only for the radial field Component in the middle of the air gap is accurate enough for the radial force calculation.
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analytical modelling and finite element computation of radial vibration force in fractional slot permanent magnet brushless machines
International Electric Machines and Drives Conference, 2009Co-Authors: Z Q Zhu, Z P Xia, G W JewellAbstract:Analytical models have been developed for analysing the radial vibration force in fractional-slot permanent magnet machines and validated extensively by finite element analyses. They are used to investigate the influence of (a) stator slotting, (b) tangential field Component, (c) radius in the airgap for computation, and (d) load condition etc. on the radial vibration force calculation. The major findings can be summarised as follows. (1) Even on open-circuit, the low Harmonic Component (e.g. 2nd for 10-pole/12-slot machine, and 1st for 8-pole/9-slot machine) of radial force exists due to slotting effect although the amplitude is relatively low, while the slotless analytical model cannot predict this phenomenon; (2) However, on load, slotless analytical model is accurate enough in the radial force analysis, since in this case, the low order Harmonic Component of radial force is mainly due to the interaction between the magnet field and the armature reaction field, and is largely determined by the combination of pole and slot numbers; (3) It is much more reliable to calculate the radial force in the middle of airgap, rather than close to the stator bore, while the Harmonic contents of radial force are almost independent of radius in the airgap; (4) The simple formula accounts only for the radial field Component in the middle of airgap is accurate enough for radial force calculation.
Li Zhang - One of the best experts on this subject based on the ideXlab platform.
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feed forward scheme for an electrolytic capacitor less ac dc led driver to reduce output current ripple
IEEE Transactions on Power Electronics, 2014Co-Authors: Yang Yang, Xinbo Ruan, Li ZhangAbstract:In order to achieve high-efficiency, high-power-factor, high-reliability, and low-cost, a flicker-free electrolytic capacitor-less single-phase ac/dc light emitting diode (LED) driver is investigated in this paper. This driver is composed of a power-factor-correction (PFC) converter and a bidirectional converter. The bidirectional converter is used to absorb the second Harmonic Component in the output current of the PFC converter, thus producing a pure dc output to drive the LEDs. The spectrum of the output capacitor voltage of the bidirectional converter is analyzed, indicating that the output capacitor voltage contains Harmonic Components at multiples of twice the line frequency apart from the dc Component and second Harmonic Component. A feed-forward control scheme with a series of calculation operation is proposed to obtain the desired modulation signal, which contains the corresponding Harmonic Components, to ensure the bidirectional converter fully absorb the second Harmonic current in the output of the PFC converter. Finally, a 33.6 W prototype is fabricated and tested in the lab, and the experiment results show that the proposed control scheme greatly reduces the ripple of the LED driving current.
Navid R Zargari - One of the best experts on this subject based on the ideXlab platform.
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a virtual space vector modulation technique for the reduction of common mode voltages in both magnitude and third order Component
IEEE Transactions on Power Electronics, 2016Co-Authors: Kai Tian, Jiacheng Wang, Zhongyuan Cheng, Navid R ZargariAbstract:A virtual space vector modulation technique reducing both magnitude and third-order Harmonic Component of the common-mode voltage (CMV) in a two-level voltage-source inverter (VSI) is proposed in this paper. The presented method employs a set of virtual space vectors constructed from original stationary space vectors to conduct modulation. Since the created virtual vectors have the lowest instantaneous and zero average CMVs, both the magnitude and third-order Harmonic Component of the generated CMV are reduced, contributing to better overall CMV performance and common-mode filter design in VSI applications. Three variants of the proposed modulation method using different virtual space vector combinations are presented. The concept of the virtual space vector modulation technique demonstrated with two-level inverter in this paper can also be extended to multilevel inverters. Simulation and experimental results, as well as comparisons with existing methods are provided to verify the proposed technique.
Li Peng - One of the best experts on this subject based on the ideXlab platform.
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accurate and fast Harmonic detection based on the generalized trigonometric function delayed signal cancellation
IEEE Access, 2019Co-Authors: Manlin Chen, Li Peng, Bowen WangAbstract:The abundant grid-connected power electronic devices and non-linear loads used widely have caused power system Harmonic pollution. Harmonic detection is very important for selective Harmonic compensation used to improve the power quality. To detect the individual Harmonic Component accurately and fast, a Harmonic extraction based on generalized trigonometric function delayed signal cancellation (GTFDSC) is proposed to extract the fundamental Component or the desired Harmonic Component. The proposed GTFDSC can be used to accurately extract the desired Harmonic Component under various Harmonic scenarios because of its excellent filtering capability. What’s more, the parameters of the GTFDSC can be flexibly designed according to the distribution of the Harmonic series of the input signal, thereby reducing the delay time and the number of operators. Furthermore, the GTFDSC is self-adjustable to fundamental frequency deviations by introducing the frequency feedback loop, and it is able to achieve excellent filtering capability and fast dynamic performances. Lastly, the experimental results are provided to verify the effectiveness of the proposed method.
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the control technique of three phase voltage source inverter output waveform based on internal model theory
Conference of the Industrial Electronics Society, 2003Co-Authors: Xuejuan Kong, Jingjiang Wang, Li Peng, Yong Kang, Jian ChengAbstract:CVCF inverters are usually applied in critical situations, whose quality of output waveform is one of the most important aspects in evaluating its performance. This paper analyses the feasibility of the three-phase inverters' output waveform control scheme based on internal model theory in rotating frame. One scheme is present which is the combination of instantaneous feedback control internal model restraining fundamental Component disturbance and repetitive control internal model restraining Harmonic Component disturbance and asymmetrical disturbance. The experiments verify the scheme can work well. Fast response, highly accurate steady output and less distorted waveform is gained.
